Conventional yachts or sailing vessels often heel over to a comparatively large degree, often about 15.degree.-40.degree., during sailing in heavy wind, with consequential discomfort and safety hazards to the crew. In addition, the heeling-over increases the vessel propelling resistance and reduces keel efficiency as regards the ability of the latter to counter-act the drift of the vessel. This means that the heeling-over reduces the vessel sailing speed, particularly when beating to windward. The hull configurations of the vessel also need adaptation so as to be relatively efficient during sailing both with and without heeling-over.
In view thereof various sailing vessel stabilizing systems have been developed. One such prior-art stabilizing system is disclosed in Applicant's patent specifications SE 456 237 and EP 0 232 359. This system includes a tiltable mast the shrouds of which are arranged to displace a movable weight in the opposite direction across the vessel to that of the mast tilting direction. The stabilizing force thus created makes it possible to substantially eliminate heeling during normal sailing conditions. To the obvious advantages from the point of view of comfort, safety and performance that are thus created could be added the advantage of making it possible to construct and configure the hull essentially for upright sailing. Consequently, the inner space of the hull could be inreased and its performance characteristics be improved under conditions of upright sailing or travel by motor.
However, also this type and similar types of vessels meet with difficulties as regards the stabilizing systems. If a sailing vessel equipped with the stabilizing system turns sharply to one side, the centrifugal force will displace the mobile weight outwards, athwartships, with the result that during the turning movement the vessel will heel outwards in a most uncomfortable manner. When the vessel is motor operated during heavy sea and heels over alternately to one side or the other by the waves, the heel will become more pronounced because of the displacement in the direction downwards and outwards of the movable weight. This intensifies the vessel rolling motions even further in a non-desirable manner. The same is true when the boat, during spinnaker sailing, starts to oscillate, i.e. to roll from side to side. This rolling motion may then be amplified by the stabilizing system and the broach which often ends an oscillating motion could be more serious than in a conventional sailing vessel.